1
|
Akter N, Islam MSU, Rahman MS, Zohra FT, Rahman SM, Manirujjaman M, Sarkar MAR. Genome-wide identification and characterization of protein phosphatase 2C (PP2C) gene family in sunflower (Helianthus annuus L.) and their expression profiles in response to multiple abiotic stresses. PLoS One 2024; 19:e0298543. [PMID: 38507444 PMCID: PMC10954154 DOI: 10.1371/journal.pone.0298543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 01/25/2024] [Indexed: 03/22/2024] Open
Abstract
Plant protein phosphatase 2C (PP2C) plays vital roles in responding to various stresses, stimulating growth factors, phytohormones, and metabolic activities in many important plant species. However, the PP2C gene family has not been investigated in the economically valuable plant species sunflower (Helianthus annuus L.). This study used comprehensive bioinformatics tools to identify and characterize the PP2C gene family members in the sunflower genome (H. annuus r1.2). Additionally, we analyzed the expression profiles of these genes using RNA-seq data under four different stress conditions in both leaf and root tissues. A total of 121 PP2C genes were identified in the sunflower genome distributed unevenly across the 17 chromosomes, all containing the Type-2C phosphatase domain. HanPP2C genes are divided into 15 subgroups (A-L) based on phylogenetic tree analysis. Analyses of conserved domains, gene structures, and motifs revealed higher structural and functional similarities within various subgroups. Gene duplication and collinearity analysis showed that among the 53 HanPP2C gene pairs, 48 demonstrated segmental duplications under strong purifying selection pressure, with only five gene pairs showing tandem duplications. The abundant segmental duplication was observed compared to tandem duplication, which was the major factor underlying the dispersion of the PP2C gene family in sunflowers. Most HanPP2C proteins were localized in the nucleus, cytoplasm, and chloroplast. Among the 121 HanPP2C genes, we identified 71 miRNAs targeting 86 HanPP2C genes involved in plant developmental processes and response to abiotic stresses. By analyzing cis-elements, we identified 63 cis-regulatory elements in the promoter regions of HanPP2C genes associated with light responsiveness, tissue-specificity, phytohormone, and stress responses. Based on RNA-seq data from two sunflower tissues (leaf and root), 47 HanPP2C genes exhibited varying expression levels in leaf tissue, while 49 HanPP2C genes showed differential expression patterns in root tissue across all stress conditions. Transcriptome profiling revealed that nine HanPP2C genes (HanPP2C12, HanPP2C36, HanPP2C38, HanPP2C47, HanPP2C48, HanPP2C53, HanPP2C54, HanPP2C59, and HanPP2C73) exhibited higher expression in leaf tissue, and five HanPP2C genes (HanPP2C13, HanPP2C47, HanPP2C48, HanPP2C54, and HanPP2C95) showed enhanced expression in root tissue in response to the four stress treatments, compared to the control conditions. These results suggest that these HanPP2C genes may be potential candidates for conferring tolerance to multiple stresses and further detailed characterization to elucidate their functions. From these candidates, 3D structures were predicted for six HanPP2C proteins (HanPP2C47, HanPP2C48, HanPP2C53, HanPP2C54, HanPP2C59, and HanPP2C73), which provided satisfactory models. Our findings provide valuable insights into the PP2C gene family in the sunflower genome, which could play a crucial role in responding to various stresses. This information can be exploited in sunflower breeding programs to develop improved cultivars with increased abiotic stress tolerance.
Collapse
Affiliation(s)
- Nasrin Akter
- Department of Genetic Engineering and Biotechnology, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, Bangladesh
| | - Md Shohel Ul Islam
- Department of Genetic Engineering and Biotechnology, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, Bangladesh
| | - Md. Shahedur Rahman
- Department of Genetic Engineering and Biotechnology, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, Bangladesh
| | - Fatema Tuz Zohra
- Department of Genetic Engineering and Biotechnology, Faculty of Biological Sciences, University of Rajshahi, Rajshahi, Bangladesh
| | - Shaikh Mizanur Rahman
- Department of Genetic Engineering and Biotechnology, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, Bangladesh
| | - M. Manirujjaman
- Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, Louisiana, LA, United States of America
| | - Md. Abdur Rauf Sarkar
- Department of Genetic Engineering and Biotechnology, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, Bangladesh
| |
Collapse
|
2
|
Negative regulators of TGF-β1 signaling in renal fibrosis; pathological mechanisms and novel therapeutic opportunities. Clin Sci (Lond) 2021; 135:275-303. [PMID: 33480423 DOI: 10.1042/cs20201213] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/23/2020] [Accepted: 01/08/2021] [Indexed: 02/06/2023]
Abstract
Elevated expression of the multifunctional cytokine transforming growth factor β1 (TGF-β1) is causatively linked to kidney fibrosis progression initiated by diabetic, hypertensive, obstructive, ischemic and toxin-induced injury. Therapeutically relevant approaches to directly target the TGF-β1 pathway (e.g., neutralizing antibodies against TGF-β1), however, remain elusive in humans. TGF-β1 signaling is subjected to extensive negative control at the level of TGF-β1 receptor, SMAD2/3 activation, complex assembly and promoter engagement due to its critical role in tissue homeostasis and numerous pathologies. Progressive kidney injury is accompanied by the deregulation (loss or gain of expression) of several negative regulators of the TGF-β1 signaling cascade by mechanisms involving protein and mRNA stability or epigenetic silencing, further amplifying TGF-β1/SMAD3 signaling and fibrosis. Expression of bone morphogenetic proteins 6 and 7 (BMP6/7), SMAD7, Sloan-Kettering Institute proto-oncogene (Ski) and Ski-related novel gene (SnoN), phosphate tensin homolog on chromosome 10 (PTEN), protein phosphatase magnesium/manganese dependent 1A (PPM1A) and Klotho are dramatically decreased in various nephropathies in animals and humans albeit with different kinetics while the expression of Smurf1/2 E3 ligases are increased. Such deregulations frequently initiate maladaptive renal repair including renal epithelial cell dedifferentiation and growth arrest, fibrotic factor (connective tissue growth factor (CTGF/CCN2), plasminogen activator inhibitor type-1 (PAI-1), TGF-β1) synthesis/secretion, fibroproliferative responses and inflammation. This review addresses how loss of these negative regulators of TGF-β1 pathway exacerbates renal lesion formation and discusses the therapeutic value in restoring the expression of these molecules in ameliorating fibrosis, thus, presenting novel approaches to suppress TGF-β1 hyperactivation during chronic kidney disease (CKD) progression.
Collapse
|
3
|
Chavalit T, Nimsamer P, Sirivassanametha K, Anuntakarun S, Saengchoowong S, Tangkijvanich P, Payungporn S. Hepatitis B Virus-Encoded MicroRNA (HBV-miR-3) Regulates Host Gene PPM1A Related to Hepatocellular Carcinoma. Microrna 2021; 9:232-239. [PMID: 31686644 DOI: 10.2174/2211536608666191104105334] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 07/30/2019] [Accepted: 10/16/2019] [Indexed: 01/05/2023]
Abstract
BACKGROUND Hepatitis B is a liver infection disease caused by the Hepatitis B Virus (HBV) that can become chronic and develop into hepatocellular carcinoma. HBV was classified as a double-stranded DNA virus. Currently, there is a report showing that HBV virus-encoded miRNA called HBV-miR-3 controls the replication of HBV. However, the regulation of HBV-miR-3 in host cells remains unclear. OBJECTIVE This study aimed to investigate the regulation of HBV-miR-3 in host gene target which is related to chronic HBV infection and HCC process. METHODS In this study, we analyzed the read count of HBV-miR-3 from next-generation sequencing of chronic hepatitis patients in Pegylated interferon alpha-2a (PEG-IFN-α-2a) treatment. To understand the regulation of HBV-miR-3 in host cells, the HBV-miR-3 recognition sites were predicted in host target genes using miRDB. The effect of HBV-miR-3 in host cells was examined using qPCR and 3' UTR dual luciferase assay. RESULTS The read count of HBV-miR-3 was found in chronic hepatitis patients before treatment. Moreover, the decrease of HBV-miR-3 was correlated with response group of chronic hepatitis patients after treatment. On the other hand, the abundance of HBV-miR-3 showed no difference in nonresponse group of chronic patients after PEG-IFN-α-2a treatment. To study the role of HBV-miR-3 in patients, four HBV-miR-3 target regions from Protein phosphatase 1A (PPM1A) and DIX domain containing 1 (DIXDC1) were identified in the human genome using miRDB. Interestingly, we found that HBV-miR-3 hybridized with PPM1A mRNA. The mRNA expression from RT-qPCR showed no difference between HepG2 transfected with pSilencer_scramble or pSilencer_HBV-miR-3. However, the reporter assay showed that PPM1A mRNA was suppressed by HBV-miR-3. The protein expression of PPM1A showed a decrease in cells overexpressing HBV-miR-3. Finally, the HBV-miR-3 can promote cell proliferation in cells overexpressing HBV-miR-3. CONCLUSION This study is the first report showed the HBV encoded miRNA can regulate host gene expression. HBV-miR-3 silenced PPM1A by inhibiting the translation process of PPM1A. The downregulation of PPM1A promotes cell proliferation related to HCC development.
Collapse
Affiliation(s)
- Tanit Chavalit
- Center of Excellence in Systems Biology, Research Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.,Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
| | - Pattaraporn Nimsamer
- Center of Excellence in Systems Biology, Research Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
| | - Kritsada Sirivassanametha
- Center of Excellence in Systems Biology, Research Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.,Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
| | - Songtham Anuntakarun
- Center of Excellence in Systems Biology, Research Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
| | - Suthat Saengchoowong
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
| | - Pisit Tangkijvanich
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.,Center of Excellence of Hepatitis and Liver Cancer, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
| | - Sunchai Payungporn
- Center of Excellence in Systems Biology, Research Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.,Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
| |
Collapse
|
4
|
Neumann J, Boknik P, Kirchhefer U, Gergs U. The role of PP5 and PP2C in cardiac health and disease. Cell Signal 2021; 85:110035. [PMID: 33964402 DOI: 10.1016/j.cellsig.2021.110035] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/16/2021] [Accepted: 05/03/2021] [Indexed: 02/08/2023]
Abstract
Protein phosphatases are important, for example, as functional antagonists of β-adrenergic stimulation of the mammalian heart. While β-adrenergic stimulations increase the phosphorylation state of regulatory proteins and therefore force of contraction in the heart, these phosphorylations are reversed and thus force is reduced by the activity of protein phosphatases. In this context the role of PP5 and PP2C is starting to unravel. They do not belong to the same family of phosphatases with regard to sequence homology, many similarities with regard to location, activation by lipids and putative substrates have been worked out over the years. We also suggest which pathways for regulation of PP5 and/or PP2C described in other tissues and not yet in the heart might be useful to look for in cardiac tissue. Both phosphatases might play a role in signal transduction of sarcolemmal receptors in the heart. Expression of PP5 and PP2C can be increased by extracellular stimuli in the heart. Because PP5 is overexpressed in failing animal and human hearts, and because overexpression of PP5 or PP2C leads to cardiac hypertrophy and KO of PP5 leads to cardiac hypotrophy, one might argue for a role of PP5 and PP2C in heart failure. Because PP5 and PP2C can reduce, at least in vitro, the phosphorylation state of proteins thought to be relevant for cardiac arrhythmias, a role of these phosphatases for cardiac arrhythmias is also probable. Thus, PP5 and PP2C might be druggable targets to treat important cardiac diseases like heart failure, cardiac hypertrophy and cardiac arrhythmias.
Collapse
Affiliation(s)
- Joachim Neumann
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, Magdeburger Str. 4, D-06097 Halle, Germany.
| | - Peter Boknik
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Westfälische Wilhelms-Universität, Domagkstraße 12, D-48149 Münster, Germany.
| | - Uwe Kirchhefer
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Westfälische Wilhelms-Universität, Domagkstraße 12, D-48149 Münster, Germany.
| | - Ulrich Gergs
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, Magdeburger Str. 4, D-06097 Halle, Germany.
| |
Collapse
|
5
|
Deregulation of Negative Controls on TGF-β1 Signaling in Tumor Progression. Cancers (Basel) 2018; 10:cancers10060159. [PMID: 29799477 PMCID: PMC6025439 DOI: 10.3390/cancers10060159] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 05/22/2018] [Accepted: 05/23/2018] [Indexed: 12/19/2022] Open
Abstract
The multi-functional cytokine transforming growth factor-β1 (TGF-β1) has growth inhibitory and anti-inflammatory roles during homeostasis and the early stages of cancer. Aberrant TGF-β activation in the late-stages of tumorigenesis, however, promotes development of aggressive growth characteristics and metastatic spread. Given the critical importance of this growth factor in fibrotic and neoplastic disorders, the TGF-β1 network is subject to extensive, multi-level negative controls that impact receptor function, mothers against decapentaplegic homolog 2/3 (SMAD2/3) activation, intracellular signal bifurcation into canonical and non-canonical pathways and target gene promotor engagement. Such negative regulators include phosphatase and tensin homologue (PTEN), protein phosphatase magnesium 1A (PPM1A), Klotho, bone morphogenic protein 7 (BMP7), SMAD7, Sloan-Kettering Institute proto-oncogene/ Ski related novel gene (Ski/SnoN), and bone morphogenetic protein and activin membrane-bound Inhibitor (BAMBI). The progression of certain cancers is accompanied by loss of expression, overexpression, mislocalization, mutation or deletion of several endogenous repressors of the TGF-β1 cascade, further modulating signal duration/intensity and phenotypic reprogramming. This review addresses how their aberrant regulation contributes to cellular plasticity, tumor progression/metastasis and reversal of cell cycle arrest and discusses the unexplored therapeutic value of restoring the expression and/or function of these factors as a novel approach to cancer treatment.
Collapse
|
6
|
Lu X, Yarbrough WG. Negative regulation of RelA phosphorylation: emerging players and their roles in cancer. Cytokine Growth Factor Rev 2014; 26:7-13. [PMID: 25438737 DOI: 10.1016/j.cytogfr.2014.09.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Accepted: 09/03/2014] [Indexed: 01/25/2023]
Abstract
NF-κB signaling contributes to human disease processes, notably inflammatory diseases and cancer. Many advances have been made in understanding mechanisms responsible for abnormal NF-κB activation with RelA post-translational modification, particularly phosphorylation, proven to be critical for RelA function. While the majority of studies have focused on identifying kinases responsible for NF-κB phosphorylation and pathway activation, recently progress has also been made in understanding the negative regulators important for restraining RelA activity. Here we summarize negative regulators of RelA phosphorylation, their targeting sites in RelA and biological functions through negative regulation of RelA activation. Finally, we emphasize the tumor suppressor-like roles that these negative regulators can assume in human cancers.
Collapse
Affiliation(s)
- Xinyuan Lu
- Department of Cancer Biology, Vanderbilt University, Nashville, TN, USA; Department of Medicine, University of California at San Francisco, San Francisco, CA, USA
| | - Wendell G Yarbrough
- Division of Otolaryngology, Department of Surgery, Yale University, New Haven, CT, USA; Department of Pathology, Yale University, New Haven, CT, USA; Yale Cancer Center, New Haven, CT, USA.
| |
Collapse
|
7
|
Enzymatic and functional analysis of a protein phosphatase, Pph3, from Myxococcus xanthus. J Bacteriol 2011; 193:2657-61. [PMID: 21398555 DOI: 10.1128/jb.01357-10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A protein phosphatase, designated Pph3, from Myxococcus xanthus showed the enzymatic characteristics of PP2C-type serine/threonine protein phosphatases, which are metal ion-dependent, okadaic acid-insensitive protein phosphatases. The pph3 mutant under starvation conditions formed immature fruiting bodies and reduced sporulation.
Collapse
|
8
|
Lammers T, Lavi S. Role of type 2C protein phosphatases in growth regulation and in cellular stress signaling. Crit Rev Biochem Mol Biol 2008; 42:437-61. [PMID: 18066953 DOI: 10.1080/10409230701693342] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A number of interesting features, phenotypes, and potential clinical applications have recently been ascribed to the type 2C family of protein phosphatases. Thus far, 16 different PP2C genes have been identified in the human genome, encoding (by means of alternative splicing) for at least 22 different isozymes. Virtually ever since their discovery, type 2C phosphatases have been predominantly linked to cell growth and to cellular stress signaling. Here, we provide an overview of the involvement of type 2C phosphatases in these two processes, and we show that four of them (PP2Calpha, PP2Cbeta, ILKAP, and PHLPP) can be expected to function as tumor suppressor proteins, and one as an oncoprotein (PP2Cdelta /Wip1). In addition, we demonstrate that in virtually all cases in which they have been linked to the stress response, PP2Cs act as inhibitors of cellular stress signaling. Based on the vast amount of experimental evidence obtained thus far, it therefore seems justified to conclude that type 2C protein phosphatases are important physiological regulators of cell growth and of cellular stress signaling.
Collapse
Affiliation(s)
- Twan Lammers
- Department of Innovative Cancer Diagnosis and Therapy, German Cancer Research Center, Heidelberg, Germany.
| | | |
Collapse
|
9
|
Saito JI, Toriumi S, Awano K, Ichijo H, Sasaki K, Kobayashi T, Tamura S. Regulation of apoptosis signal-regulating kinase 1 by protein phosphatase 2Cepsilon. Biochem J 2007; 405:591-6. [PMID: 17456047 PMCID: PMC2267319 DOI: 10.1042/bj20070231] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
ASK1 (apoptosis signal-regulating kinase 1), a MKKK (mitogen-activated protein kinase kinase kinase), is activated in response to cytotoxic stresses, such as H2O2 and TNFalpha (tumour necrosis factor alpha). ASK1 induction initiates a signalling cascade leading to apoptosis. After exposure of cells to H2O2, ASK1 is transiently activated by autophosphorylation at Thr845. The protein then associates with PP5 (protein serine/threonine phosphatase 5), which inactivates ASK1 by dephosphorylation of Thr845. Although this feedback regulation mechanism has been elucidated, it remains unclear how ASK1 is maintained in the dephosphorylated state under non-stressed conditions. In the present study, we have examined the possible role of PP2Cepsilon (protein phosphatase 2Cepsilon), a member of PP2C family, in the regulation of ASK1 signalling. Following expression in HEK-293 cells (human embryonic kidney cells), wild-type PP2Cepsilon inhibited ASK1-induced activation of an AP-1 (activator protein 1) reporter gene. Conversely, a dominant-negative PP2Cepsilon mutant enhanced AP-1 activity. Exogenous PP2Cepsilon associated with exogenous ASK1 in HEK-293 cells under non-stressed conditions, inactivating ASK1 by decreasing Thr845 phosphorylation. The association of endogenous PP2Cepsilon and ASK1 was also observed in mouse brain extracts. PP2Cepsilon directly dephosphorylated ASK1 at Thr845 in vitro. In contrast with PP5, PP2Cepsilon transiently dissociated from ASK1 within cells upon H2O2 treatment. These results suggest that PP2Cepsilon maintains ASK1 in an inactive state by dephosphorylation in quiescent cells, supporting the possibility that PP2Cepsilon and PP5 play different roles in H2O2-induced regulation of ASK1 activity.
Collapse
Affiliation(s)
- Jun-ichi Saito
- *Department of Biochemistry, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan
- †Division of Advanced Prosthetic Dentistry, Graduate School of Dentistry, Tohoku University, 4-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan
| | - Shinnosuke Toriumi
- *Department of Biochemistry, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan
- ‡Division of Periodontology and Endodontology, Graduate School of Dentistry, Tohoku University, 4-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan
| | - Kenjiro Awano
- *Department of Biochemistry, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan
- §Division of Oral Surgery, Graduate School of Dentistry, Tohoku University, 4-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan
| | - Hidenori Ichijo
- ∥Laboratory of Cell Signaling, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan
| | - Keiichi Sasaki
- †Division of Advanced Prosthetic Dentistry, Graduate School of Dentistry, Tohoku University, 4-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan
| | - Takayasu Kobayashi
- *Department of Biochemistry, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan
| | - Shinri Tamura
- *Department of Biochemistry, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan
- To whom correspondence should be addressed (email )
| |
Collapse
|
10
|
Stern A, Privman E, Rasis M, Lavi S, Pupko T. Evolution of the Metazoan Protein Phosphatase 2C Superfamily. J Mol Evol 2006; 64:61-70. [PMID: 17160364 DOI: 10.1007/s00239-006-0033-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Accepted: 10/04/2006] [Indexed: 01/22/2023]
Abstract
Members of the protein phosphatase 2C (PP2C) superfamily are Mg(2+)/Mn(2+)-dependent serine/threonine phosphatases, which are essential for regulation of cell cycle and stress signaling pathways in cells. In this study, a comprehensive genomic analysis of all available metazoan PP2C sequences was conducted. The phylogeny of PP2C was reconstructed, revealing the existence of 15 vertebrate families which arose following a series of gene duplication events. Relative dating of these duplications showed that they occurred in two active periods: before the divergence of bilaterians and before vertebrate diversification. PP2C families which duplicated during the first period take part in different signaling pathways, whereas PP2C families which diverged in the second period display tissue expression differences yet participate in similar signaling pathways. These differences were found to involve variation of expression in tissues which show higher complexity in vertebrates, such as skeletal muscle and the nervous system. Further analysis was performed with the aim of identifying the functional domains of PP2C. The conservation pattern across the entire PP2C superfamily revealed an extensive domain of more than 50 amino acids which is highly conserved throughout all PP2C members. Several insertion or deletion events were found which may have led to the specialization of each PP2C family.
Collapse
Affiliation(s)
- Adi Stern
- Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | | | | | | | | |
Collapse
|
11
|
Tamura S, Toriumi S, Saito JI, Awano K, Kudo TA, Kobayashi T. PP2C family members play key roles in regulation of cell survival and apoptosis. Cancer Sci 2006; 97:563-7. [PMID: 16827794 PMCID: PMC11159723 DOI: 10.1111/j.1349-7006.2006.00219.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Although unlimited proliferation of cancer cells is supported by multiple signaling pathways involved in the regulation of proliferation, survival, and apoptosis, the molecular mechanisms coordinating these different pathways to promote the proliferation and survival of cancer cells have remained unclear. SAPK and integrin-ILK signaling pathways play key roles in the promotion of apoptosis and cell proliferation/survival, respectively. Studies of TNFalpha- and H2O2-induced apoptosis revealed that ASK1, a component of the SAPK system, mediates the TNFalpha and H2O2 signaling of apoptosis. ASK1 is activated by autophosphorylation of a specific threonine residue (T845) following TNFalpha stimulation. Our recent studies indicate that PP2Cepsilon, a member of the PP2C family, associates with and inactivates ASK1 by dephosphorylating T845. In contrast, PP2Cdelta/ILKAP, a second PP2C family member, activates ASK1 by enhancing cellular phosphorylation of T845. PP2Cdelta/ILKAP also forms a complex with ILK1 to inhibit the GSK3beta-mediated integrin-ILK1 signaling in vivo, inhibiting cell cycle progression. These observations raise the possibility that PP2Cdelta/ILKAP acts to control the cross-talk between integrin-induced and TNFalpha-induced signaling pathways, inhibiting the former and stimulating the latter, thereby inhibiting proliferation and survival and promoting the apoptosis of cancer cells.
Collapse
Affiliation(s)
- Shinri Tamura
- Department of Biochemistry, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan.
| | | | | | | | | | | |
Collapse
|
12
|
Li R, Potters MB, Shi L, Kennelly PJ. The protein phosphatases of Synechocystis sp. strain PCC 6803: open reading frames sll1033 and sll1387 encode enzymes that exhibit both protein-serine and protein-tyrosine phosphatase activity in vitro. J Bacteriol 2005; 187:5877-84. [PMID: 16109928 PMCID: PMC1196173 DOI: 10.1128/jb.187.17.5877-5884.2005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The open reading frames (ORFs) encoding two potential protein-serine/threonine phosphatases from the cyanobacterium Synechocystis sp. strain PCC 6803 were cloned and their protein products expressed in Escherichia coli cells. The product of ORF sll1033, SynPPM3, is a homologue of the PPM family of protein-serine/threonine phosphatases found in all eukaryotes as well as many members of the Bacteria. Surprisingly, the recombinant protein phosphatase dephosphorylated phosphotyrosine- as well as phosphoserine-containing proteins in vitro. While kinetic analyses indicate that the enzyme was more efficient at dephosphorylating the latter, replacement of Asp608 by asparagine enhanced activity toward a phosphotyrosine-containing protein fourfold. The product of ORF sll1387, SynPPP1, is the sole homolog of the PPP family of protein phosphatases encoded by the genome of Synechocystis sp. strain PCC 6803. Like many other bacterial PPPs, the enzyme dephosphorylated phosphoserine- and phosphotyrosine-containing proteins with comparable efficiencies. However, while previously described PPPs from prokaryotic organisms required the addition of exogenous metal ion cofactors, such as Mg2+ or Mn2+, for activity, recombinantly produced SynPPP1 displayed near-maximal activity in the absence of added metals. Inductively coupled plasma mass spectrometry indicated that recombinant SynPPP1 contained significant quantities, 0.32 to 0.44 mol/mole total, of Mg and Mn. In this respect, the cyanobacterial enzyme resembled eukaryotic members of the PPP family, which are metalloproteins. mRNA encoding SynPPP1 or SynPPM3 could be detected in cells grown under many, but not all, environmental conditions.
Collapse
Affiliation(s)
- Renhui Li
- Department of Biochemistry-0308, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | | | | | | |
Collapse
|
13
|
Prajapati S, Verma U, Yamamoto Y, Kwak YT, Gaynor RB. Protein Phosphatase 2Cβ Association with the IκB Kinase Complex Is Involved in Regulating NF-κB Activity. J Biol Chem 2004; 279:1739-46. [PMID: 14585847 DOI: 10.1074/jbc.m306273200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The NF-kappaB pathway is important in the control of the immune and inflammatory response. One of the critical events in the activation of this pathway is the stimulation of the IkappaB kinases (IKKs) by cytokines such as tumor necrosis factor-alpha and interleukin-1. Although the mechanisms that modulate IKK activation have been studied in detail, much less is known about the processes that down-regulate its activity following cytokine treatment. In this study, we utilized biochemical fractionation and mass spectrometry to demonstrate that protein phosphatase 2Cbeta (PP2Cbeta) can associate with the IKK complex. PP2Cbeta association with the IKK complex led to the dephosphorylation of IKKbeta and decreased its kinase activity. The binding of PP2Cbeta to IKKbeta was decreased at early times post-tumor necrosis factor-alpha treatment and was restored at later times following treatment with this cytokine. Experiments utilizing siRNA directed against PP2Cbeta demonstrated an in vivo role for this phosphatase in decreasing IKK activity at late times following cytokine treatment. These studies are consistent with the ability of PP2Cbeta to down-regulate cytokine-induced NF-kappaB activation by altering IKK activity.
Collapse
Affiliation(s)
- Shashi Prajapati
- Division of Hematology-Oncology, Department of Medicine, Harold Simmons Cancer Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-8594, USA
| | | | | | | | | |
Collapse
|
14
|
Komaki KI, Katsura K, Ohnishi M, Guang Li M, Sasaki M, Watanabe M, Kobayashi T, Tamura S. Molecular cloning of PP2Cη, a novel member of the protein phosphatase 2C family. ACTA ACUST UNITED AC 2003; 1630:130-7. [PMID: 14654243 DOI: 10.1016/j.bbaexp.2003.09.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have cloned a novel member of the mouse protein phosphatase 2C family, PP2Ceta. Sequence analysis suggests that PP2Ceta, PP2Czeta and NERPP-2C constitute a unique subgroup of the PP2C family. PP2Ceta had extremely low activity against alpha-casein compared with PP2Calpha and was localized mainly in cell nuclei, suggesting that PP2Ceta dephosphorylates a unique nuclear protein(s) in the cells.
Collapse
Affiliation(s)
- Ken-ichiro Komaki
- Department of Biochemistry, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Sim ATR, Baldwin ML, Rostas JAP, Holst J, Ludowyke RI. The role of serine/threonine protein phosphatases in exocytosis. Biochem J 2003; 373:641-59. [PMID: 12749763 PMCID: PMC1223558 DOI: 10.1042/bj20030484] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2003] [Revised: 05/09/2003] [Accepted: 05/16/2003] [Indexed: 10/27/2022]
Abstract
Modulation of exocytosis is integral to the regulation of cellular signalling, and a variety of disorders (such as epilepsy, hypertension, diabetes and asthma) are closely associated with pathological modulation of exocytosis. Emerging evidence points to protein phosphatases as key regulators of exocytosis in many cells and, therefore, as potential targets for the design of novel therapies to treat these diseases. Diverse yet exquisite regulatory mechanisms have evolved to direct the specificity of these enzymes in controlling particular cell processes, and functionally driven studies have demonstrated differential regulation of exocytosis by individual protein phosphatases. This Review discusses the evidence for the regulation of exocytosis by protein phosphatases in three major secretory systems, (1) mast cells, in which the regulation of exocytosis of inflammatory mediators plays a major role in the respiratory response to antigens, (2) insulin-secreting cells in which regulation of exocytosis is essential for metabolic control, and (3) neurons, in which regulation of exocytosis is perhaps the most complex and is essential for effective neurotransmission.
Collapse
Affiliation(s)
- Alistair T R Sim
- School of Biomedical Sciences, Faculty of Health, University of Newcastle, and Clinical Neuroscience Program, Hunter Medical Research Institute, Callaghan, NSW 2308, Australia.
| | | | | | | | | |
Collapse
|
16
|
Li MG, Katsura K, Nomiyama H, Komaki KI, Ninomiya-Tsuji J, Matsumoto K, Kobayashi T, Tamura S. Regulation of the interleukin-1-induced signaling pathways by a novel member of the protein phosphatase 2C family (PP2Cepsilon). J Biol Chem 2003; 278:12013-21. [PMID: 12556533 DOI: 10.1074/jbc.m211474200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although TAK1 signaling plays essential roles in eliciting cellular responses to interleukin-1 (IL-1), a proinflammatory cytokine, how the IL-1-TAK1 signaling pathway is positively and negatively regulated remains poorly understood. In this study, we investigated the possible role of a novel protein phosphatase 2C (PP2C) family member, PP2Cepsilon, in the regulation of the IL-1-TAK1 signaling pathway. PP2Cepsilon was composed of 303 amino acids, and the overall similarity of amino acid sequence between PP2Cepsilon and PP2Calpha was found to be 26%. Ectopic expression of PP2Cepsilon inhibited the IL-1- and TAK1-induced activation of mitogen-activated protein kinase kinase 4 (MKK4)-c-Jun N-terminal kinase or MKK3-p38 signaling pathway. PP2Cepsilon dephosphorylated TAK1 in vitro. Co-immunoprecipitation experiments indicated that PP2Cepsilon associates stably with TAK1 and attenuates the binding of TAK1 to MKK4 or MKK6. Ectopic expression of a phosphatase-negative mutant of PP2Cepsilon, PP2Cepsilon(D/A), which acted as a dominant negative form, enhanced both the association between TAK1 and MKK4 or MKK6 and the TAK1-induced activation of an AP-1 reporter gene. The association between PP2Cepsilon and TAK1 was transiently suppressed by IL-1 treatment of the cells. Taken together, these results suggest that, in the absence of IL-1-induced signal, PP2Cepsilon contributes to keeping the TAK1 signaling pathway in an inactive state by associating with and dephosphorylating TAK1.
Collapse
Affiliation(s)
- Ming Guang Li
- Department of Biochemistry, Institute of Development, Aging, and Cancer, Tohoku University, 4-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Young C, Mapes J, Hanneman J, Al-Zarban S, Ota I. Role of Ptc2 type 2C Ser/Thr phosphatase in yeast high-osmolarity glycerol pathway inactivation. EUKARYOTIC CELL 2002; 1:1032-40. [PMID: 12477803 PMCID: PMC138758 DOI: 10.1128/ec.1.6.1032-1040.2002] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2002] [Accepted: 09/10/2002] [Indexed: 11/20/2022]
Abstract
Three type 2C Ser/Thr phosphatases (PTCs) are negative regulators of the yeast Saccharomyces cerevisiae high-osmolarity glycerol mitogen-activated protein kinase (MAPK) pathway. Ptc2 and Ptc3 are 75% identical to each other and differ from Ptc1 in having a noncatalytic domain. Previously, we showed that Ptc1 inactivates the pathway by dephosphorylating the Hog1 MAPK; Ptc1 maintains low basal Hog1 activity and dephosphorylates Hog1 during adaptation. Here, we examined the function of Ptc2 and Ptc3. First, deletion of PTC2 and/or PTC3 together with PTP2, encoding the protein tyrosine phosphatase that inactivates Hog1, produced a strong growth defect at 37 degrees C that was dependent on HOG1, providing further evidence that PTC2 and PTC3 are negative regulators. Second, overexpression of PTC2 inhibited Hog1 activation but did not affect Hog1-Tyr phosphorylation, suggesting that Ptc2 inactivates the pathway by dephosphorylating the Hog1 activation loop phosphothreonine (pThr) residue. Indeed, in vitro studies confirmed that Ptc2 was specific for Hog1-pThr. Third, deletion of both PTC2 and PTC3 led to greater Hog1 activation upon osmotic stress than was observed in wild-type strains, although no obvious change in Hog1 inactivation during adaptation was seen. These results indicate that Ptc2 and Ptc3 differ from Ptc1 in that they limit maximal Hog1 activity. The function of the Ptc2 noncatalytic domain was also examined. Deletion of this domain decreased V(max) by 1.6-fold and increased K(m) by 2-fold. Thus Ptc2 requires an additional amino acid sequence beyond the catalytic domain defined for PTCs for full activity.
Collapse
Affiliation(s)
- Christian Young
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA
| | | | | | | | | |
Collapse
|
18
|
Tamura S, Hanada M, Ohnishi M, Katsura K, Sasaki M, Kobayashi T. Regulation of stress-activated protein kinase signaling pathways by protein phosphatases. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:1060-6. [PMID: 11856337 DOI: 10.1046/j.0014-2956.2002.02754.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Stress-activated protein kinase (SAPK) signaling plays essential roles in eliciting adequate cellular responses to stresses and proinflammatory cytokines. SAPK pathways are composed of three successive protein kinase reactions. The phosphorylation of SAPK signaling components on Ser/Thr or Thr/Tyr residues suggests the involvement of various protein phosphatases in the negative regulation of these systems. Accumulating evidence indicates that three families of protein phosphatases, namely the Ser/Thr phosphatases, the Tyr phosphatases and the dual specificity Ser/Thr/Tyr phosphatases regulate these pathways, each mediating a distinct function. Differences in substrate specificities and regulatory mechanisms for these phosphatases form the molecular basis for the complex regulation of SAPK signaling. Here we describe the properties of the protein phosphatases responsible for the regulation of SAPK signaling pathways.
Collapse
Affiliation(s)
- Shinri Tamura
- Department of Biochemistry, Institute of Development, Aging and Cancer, Tohoku University, Aoba-ku, Sendai, Japan.
| | | | | | | | | | | |
Collapse
|
19
|
Tan KM, Chan SL, Tan KO, Yu VC. The Caenorhabditis elegans sex-determining protein FEM-2 and its human homologue, hFEM-2, are Ca2+/calmodulin-dependent protein kinase phosphatases that promote apoptosis. J Biol Chem 2001; 276:44193-202. [PMID: 11559703 DOI: 10.1074/jbc.m105880200] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In Caenorhabditis elegans, fem-1, fem-2, and fem-3 play pivotal roles in sex determination. Recently, a mammalian homologue of the C. elegans sex-determining protein FEM-1, F1Aalpha, has been described. Although there is little evidence to link F1Aalpha to sex determination, F1Aalpha and FEM-1 both promote apoptosis in mammalian cells. Here we report the identification and characterization of a human homologue of the C. elegans sex-determining protein FEM-2, hFEM-2. Similar to FEM-2, hFEM-2 exhibited PP2C phosphatase activity and associated with FEM-3. hFEM-2 shows striking similarity (79% amino acid identity) to rat Ca(2+)/calmodulin (CaM)-dependent protein kinase phosphatase (rCaMKPase). hFEM-2 and FEM-2, but not PP2Calpha, were demonstrated to dephosphorylate CaM kinase II efficiently in vitro, suggesting that hFEM-2 and FEM-2 are specific phosphatases for CaM kinase. Furthermore, hFEM-2 and FEM-2 associated with F1Aalpha and FEM-1 respectively. Overexpression of hFEM-2, FEM-2, or rCaMKPase all mediated apoptosis in mammalian cells. The catalytically active, but not the inactive, forms of hFEM-2 induced caspase-dependent apoptosis, which was blocked by Bcl-XL or a dominant negative mutant of caspase-9. Taken together, our data suggest that hFEM-2 and rCaMKPase are mammalian homologues of FEM-2 and they are evolutionarily conserved CaM kinase phosphatases that may have a role in apoptosis signaling.
Collapse
Affiliation(s)
- K M Tan
- Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609, Republic of Singapore
| | | | | | | |
Collapse
|
20
|
Rocha CR, Schröppel K, Harcus D, Marcil A, Dignard D, Taylor BN, Thomas DY, Whiteway M, Leberer E. Signaling through adenylyl cyclase is essential for hyphal growth and virulence in the pathogenic fungus Candida albicans. Mol Biol Cell 2001; 12:3631-43. [PMID: 11694594 PMCID: PMC60281 DOI: 10.1091/mbc.12.11.3631] [Citation(s) in RCA: 291] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The human fungal pathogen Candida albicans switches from a budding yeast form to a polarized hyphal form in response to various external signals. This morphogenetic switching has been implicated in the development of pathogenicity. We have cloned the CaCDC35 gene encoding C. albicans adenylyl cyclase by functional complementation of the conditional growth defect of Saccharomyces cerevisiae cells with mutations in Ras1p and Ras2p. It has previously been shown that these Ras homologues regulate adenylyl cyclase in yeast. The C. albicans adenylyl cyclase is highly homologous to other fungal adenylyl cyclases but has less sequence similarity with the mammalian enzymes. C. albicans cells deleted for both alleles of CaCDC35 had no detectable cAMP levels, suggesting that this gene encodes the only adenylyl cyclase in C. albicans. The homozygous mutant cells were viable but grew more slowly than wild-type cells and were unable to switch from the yeast to the hyphal form under all environmental conditions that we analyzed in vitro. Moreover, this morphogenetic switch was completely blocked in mutant cells undergoing phagocytosis by macrophages. However, morphogenetic switching was restored by exogenous cAMP. On the basis of epistasis experiments, we propose that CaCdc35p acts downstream of the Ras homologue CaRas1p. These epistasis experiments also suggest that the putative transcription factor Efg1p and components of the hyphal-inducing MAP kinase pathway depend on the function of CaCdc35p in their ability to induce morphogenetic switching. Homozygous cacdc35 Delta cells were unable to establish vaginal infection in a mucosal membrane mouse model and were avirulent in a mouse model for systemic infections. These findings suggest that fungal adenylyl cyclases and other regulators of the cAMP signaling pathway may be useful targets for antifungal drugs.
Collapse
Affiliation(s)
- C R Rocha
- Eukaryotic Genetics Group, Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec H4P 2R2, Canada
| | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Jackson MD, Denu JM. Molecular reactions of protein phosphatases--insights from structure and chemistry. Chem Rev 2001; 101:2313-40. [PMID: 11749375 DOI: 10.1021/cr000247e] [Citation(s) in RCA: 168] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M D Jackson
- Department of Biochemistry and Molecular Biology, Oregon Health Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97201, USA
| | | |
Collapse
|
22
|
Hanada M, Ninomiya-Tsuji J, Komaki K, Ohnishi M, Katsura K, Kanamaru R, Matsumoto K, Tamura S. Regulation of the TAK1 signaling pathway by protein phosphatase 2C. J Biol Chem 2001; 276:5753-9. [PMID: 11104763 DOI: 10.1074/jbc.m007773200] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein phosphatase 2C (PP2C) is implicated in the negative regulation of stress-activated protein kinase cascades in yeast and mammalian cells. In this study, we determined the role of PP2Cbeta-1, a major isoform of mammalian PP2C, in the TAK1 signaling pathway, a stress-activated protein kinase cascade that is activated by interleukin-1, transforming growth factor-beta, or stress. Ectopic expression of PP2Cbeta-1 inhibited the TAK1-mediated mitogen-activated protein kinase kinase 4-c-Jun amino-terminal kinase and mitogen-activated protein kinase kinase 6-p38 signaling pathways. In vitro, PP2Cbeta-1 dephosphorylated and inactivated TAK1. Coimmunoprecipitation experiments indicated that PP2Cbeta-1 associates with the central region of TAK1. A phosphatase-negative mutant of PP2Cbeta-1, PP2Cbeta-1 (R/G), acted as a dominant negative mutant, inhibiting dephosphorylation of TAK1 by wild-type PP2Cbeta-1 in vitro. In addition, ectopic expression of PP2Cbeta-1(R/G) enhanced interleukin-1-induced activation of an AP-1 reporter gene. Collectively, these results indicate that PP2Cbeta negatively regulates the TAK1 signaling pathway by direct dephosphorylation of TAK1.
Collapse
Affiliation(s)
- M Hanada
- Department of Biochemistry, Institute of Development, Aging, and Cancer, Tohoku University, 4-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Cheng A, Kaldis P, Solomon MJ. Dephosphorylation of human cyclin-dependent kinases by protein phosphatase type 2C alpha and beta 2 isoforms. J Biol Chem 2000; 275:34744-9. [PMID: 10934208 DOI: 10.1074/jbc.m006210200] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously reported that the activating phosphorylation on cyclin-dependent kinases in yeast (Cdc28p) and in humans (Cdk2) is removed by type 2C protein phosphatases. In this study, we characterize this PP2C-like activity in HeLa cell extract and determine that it is due to PP2C beta 2, a novel PP2C beta isoform, and to PP2C alpha. PP2C alpha and PP2C beta 2 co-purified with Mg(2+)-dependent Cdk2/Cdk6 phosphatase activity in DEAE-Sepharose, Superdex-200, and Mono Q chromatographies. Moreover, purified recombinant PP2C alpha and PP2C beta 2 proteins efficiently dephosphorylated monomeric Cdk2/Cdk6 in vitro. The dephosphorylation of Cdk2 and Cdk6 by PP2C isoforms was inhibited by the binding of cyclins. We found that the PP2C-like activity in HeLa cell extract, partially purified HeLa PP2C alpha and PP2C beta 2 isoforms, and the recombinant PP2Cs exhibited a comparable substrate preference for a phosphothreonine containing substrate, consistent with the conservation of threonine residues at the site of activating phosphorylation in CDKs.
Collapse
Affiliation(s)
- A Cheng
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520-8114, USA
| | | | | |
Collapse
|
24
|
Abstract
MAP kinases function as key signal integration points for a vast number of external stimuli that affect the life and death of cells and are therefore subject to rigorous regulation. Here we review the numerous protein phosphatases that directly counteract MAP kinase activation. To simplify the complexity, we attempt to integrate the information into a 'sequential phosphatase model' of MAP kinase regulation.
Collapse
Affiliation(s)
- M Saxena
- Laboratory of Signal Transduction, La Jolla Cancer Research Center, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | | |
Collapse
|
25
|
Klumpp S, Selke D. Purification and characterization of protein phosphatase type 2C in photoreceptors. Methods Enzymol 2000; 315:570-8. [PMID: 10736727 DOI: 10.1016/s0076-6879(00)15868-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Affiliation(s)
- S Klumpp
- Institute of Pharmaceutical Chemistry, Universität Marburg, Germany
| | | |
Collapse
|
26
|
Herzig S, Neumann J. Effects of serine/threonine protein phosphatases on ion channels in excitable membranes. Physiol Rev 2000; 80:173-210. [PMID: 10617768 DOI: 10.1152/physrev.2000.80.1.173] [Citation(s) in RCA: 207] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This review deals with the influence of serine/threonine-specific protein phosphatases on the function of ion channels in the plasma membrane of excitable tissues. Particular focus is given to developments of the past decade. Most of the electrophysiological experiments have been performed with protein phosphatase inhibitors. Therefore, a synopsis is required incorporating issues from biochemistry, pharmacology, and electrophysiology. First, we summarize the structural and biochemical properties of protein phosphatase (types 1, 2A, 2B, 2C, and 3-7) catalytic subunits and their regulatory subunits. Then the available pharmacological tools (protein inhibitors, nonprotein inhibitors, and activators) are introduced. The use of these inhibitors is discussed based on their biochemical selectivity and a number of methodological caveats. The next section reviews the effects of these tools on various classes of ion channels (i.e., voltage-gated Ca(2+) and Na(+) channels, various K(+) channels, ligand-gated channels, and anion channels). We delineate in which cases a direct interaction between a protein phosphatase and a given channel has been proven and where a more complex regulation is likely involved. Finally, we present ideas for future research and possible pathophysiological implications.
Collapse
Affiliation(s)
- S Herzig
- Institut für Pharmakologie, Universität Köln, Köln, Germany.
| | | |
Collapse
|
27
|
Murray MV, Kobayashi R, Krainer AR. The type 2C Ser/Thr phosphatase PP2Cgamma is a pre-mRNA splicing factor. Genes Dev 1999; 13:87-97. [PMID: 9887102 PMCID: PMC316367 DOI: 10.1101/gad.13.1.87] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/1998] [Accepted: 11/18/1998] [Indexed: 11/24/2022]
Abstract
To identify activities involved in human pre-mRNA splicing, we have developed a procedure to separate HeLa cell nuclear extract into five complementing fractions. An activity called SCF1 was purified from one of these fractions by assaying for reconstitution of splicing in the presence of the remaining four fractions. A component of SCF1 is shown to be PP2Cgamma, a type 2C Ser/Thr phosphatase of previously unknown function. Previous work suggested that dephosphorylation of splicing factors may be important for catalysis after spliceosome assembly, although the identities of the specific phosphatases involved remain unclear. Here we show that human PP2Cgamma is physically associated with the spliceosome in vitro throughout the splicing reaction, but is first required during the early stages of spliceosome assembly for efficient formation of the A complex. The phosphatase activity is required for the splicing function of PP2Cgamma, as an active site mutant does not support spliceosome assembly. The requirement for PP2Cgamma is highly specific, as the closely related phosphatase PP2Calpha cannot substitute for PP2Cgamma. Consistent with a role in splicing, PP2Cgamma localizes to the nucleus in vivo. We conclude that at least one specific dephosphorylation event catalyzed by PP2Cgamma is required for formation of the spliceosome.
Collapse
Affiliation(s)
- M V Murray
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724 USA
| | | | | |
Collapse
|
28
|
Abstract
PP2C is a structurally diversified protein phosphatase family with a wide range of functions in cellular signal transduction. A novel PP2C subtype, designated PP2Cdelta, was identified from a rat cDNA clone, which encodes a protein of 392 amino acid residues. While PP2Cdelta shares approximately 30% sequence identity in its catalytic domain with the mammalian PP2C, it lacks a 90-residue carboxyl-terminal sequence conserved in mammalian PP2C. Northern blot analysis showed that PP2Cdelta is widely expressed in rat tissues. The transcription of the PP2Cdelta gene was activated in response to stress, such as the addition of ethanol to the culture medium or UV irradiation of cells. Recombinant PP2Cdelta purified from bacteria exhibited a potent Mn2+-dependent serine/threonine phosphatase activity. Unlike other members of the PP2C family, the activity of PP2Cdelta was inhibited, rather than stimulated, by Mg2+. Transfection with PP2Cdelta resulted in inhibition of cell growth, precluding generation of stable 293 or CHO transfectants. Using a modified tetracycline-regulated PP2Cdelta-GFP dicistronic expression cassette, it was revealed that overexpression of PP2Cdelta blocked cell cycle progression and arrested cells at early S phase, resulting in inhibition of DNA synthesis and leading to cell death. These results suggest that PP2Cdelta plays a role in regulation of cell cycle progression via dephosphorylation of its substrates whose appropriate phosphorylation states might be crucial for cell proliferation.
Collapse
Affiliation(s)
- Y Tong
- Biotechnology Research Institute of Montreal, National Research Council of Canada, Montreal, Quebec, Canada, H4P 2R2
| | | | | |
Collapse
|
29
|
Labes M, Roder J, Roach A. A novel phosphatase regulating neurite extension on CNS inhibitors. Mol Cell Neurosci 1998; 12:29-47. [PMID: 9770338 DOI: 10.1006/mcne.1998.0692] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The inability of injured axons to regenerate in the adult mammalian central nervous system is thought to be in part due to inhibitory molecules synthesized by oligodendrocytes and present in myelin. We describe the cloning of a cDNA encoding a novel neuronal protein, named NERPP-2C, which is distantly related to protein phosphatase 2C and plays a role in the inhibitory response pathway to myelin inhibitors. NERPP-2C is expressed in neuronal cell lines and in rat brain. Expression in rat is detectable at E15, increases with age, and is highest in adulthood. Exposure of NG108-15 cells to antisense oligonucleotides reduces NERPP-2C expression and overcomes the inhibition of neurite extension on CNS myelin substrates in vitro. Antibodies to NERPP-2C detect two proteins, approximately 55 and 80 kDa in size, the smaller of which is found in the cytoplasm, and the larger is associated with the membrane fraction. The antibodies specifically immunoprecipitate a protein which exhibits serine/threonine and tyrosine phosphatase activity. NERPP-2C is localized in neurites and in growth cones, as well as in the cell nucleus. We hypothesize that NERPP-2C is a component in the signal transduction pathway for neuronal growth inhibitory factors in CNS myelin.
Collapse
Affiliation(s)
- M Labes
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada
| | | | | |
Collapse
|
30
|
Takekawa M, Maeda T, Saito H. Protein phosphatase 2Calpha inhibits the human stress-responsive p38 and JNK MAPK pathways. EMBO J 1998; 17:4744-52. [PMID: 9707433 PMCID: PMC1170803 DOI: 10.1093/emboj/17.16.4744] [Citation(s) in RCA: 226] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
MAPK (mitogen-activated protein kinase) cascades are common eukaryotic signaling modules that consist of a MAPK, a MAPK kinase (MAPKK) and a MAPKK kinase (MAPKKK). Because phosphorylation is essential for the activation of both MAPKKs and MAPKs, protein phosphatases are likely to be important regulators of signaling through MAPK cascades. To identify protein phosphatases that negatively regulate the stress-responsive p38 and JNK MAPK cascades, we screened human cDNA libraries for genes that down-regulated the yeast HOG1 MAPK pathway, which shares similarities with the p38 and JNK pathways, using a hyperactivating yeast mutant. In this screen, the human protein phosphatase type 2Calpha (PP2Calpha) was found to negatively regulate the HOG1 pathway in yeast. Moreover, when expressed in mammalian cells, PP2Calpha inhibited the activation of the p38 and JNK cascades induced by environmental stresses. Both in vivo and in vitro observations indicated that PP2Calpha dephosphorylated and inactivated MAPKKs (MKK6 and SEK1) and a MAPK (p38) in the stress-responsive MAPK cascades. Furthermore, a direct interaction of PP2Calpha and p38 was demonstrated by a co-immunoprecipitation assay. This interaction was observed only when cells were stimulated with stresses or when a catalytically inactive PP2Calpha mutant was used, suggesting that only the phosphorylated form of p38 interacts with PP2Calpha.
Collapse
Affiliation(s)
- M Takekawa
- Dana-Farber Cancer Institute and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | | | | |
Collapse
|
31
|
Grothe K, Hanke C, Momayezi M, Kissmehl R, Plattner H, Schultz JE. Functional characterization and localization of protein phosphatase type 2C from Paramecium. J Biol Chem 1998; 273:19167-72. [PMID: 9668103 DOI: 10.1074/jbc.273.30.19167] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We cloned a protein phosphatase 2C gene from Paramecium (PtPP2C), which codes for one of the smallest PP2C isoforms (Klumpp, S., Hanke, C., Donella-Deana, A., Beyer, A., Kellner, R., Pinna, L. A., and Schultz, J. E. (1994) J. Biol. Chem. 269, 32774-32780). After mutation of 9 ciliate Q codons (TAA) to CAA PtPP2C was expressed as an active protein in Escherichia coli. The catalytic core region contains 284 amino acids as defined by C- and N-terminal deletions. The C terminus from amino acid 200-300 of PP2C isoforms has only about 20% similarity. To demonstrate that the carboxy end is in fact needed for activity, we generated an enzymatically active PtPP2C containing a C-terminally located tobacco etch virus-protease site. Upon proteolytic truncation enzyme activity was lost, i.e. the C terminus of PP2C is indispensable for enzyme activity. During these experiments isoleucine 214 was fortuitously identified to be essential for PP2C catalysis. Mutation of the hydrophobic amino acid to glycine in the ciliate or bovine isoforms resulted in inactive protein. Because Ile214 is in a loop region without defined secondary structure, our data clearly go beyond the x-ray structure. The functional equivalence of the 180 amino acid long C terminus from the bovine PP2C with the 100 amino acid long carboxy end of the PtPP2C was demonstrated by producing an active chimera, i.e. the PP2C from Paramecium has no obvious regions which may be specifically involved in subcellular localization or substrate recognition. Using antibodies against recombinant PtPP2C we localized the enzyme by immunogold labeling in the cytosol and nucleus and very distinctly on the ciliary microtubule/dynein complex. The data suggest a role for PtPP2C in the regulation of dyneins, i.e. in cellular cargo transport and ciliary motility.
Collapse
Affiliation(s)
- K Grothe
- Pharmazeutisches Institut der Universität Tübingen, D-72076 Tübingen, Germany
| | | | | | | | | | | |
Collapse
|
32
|
Meskiene I, Bögre L, Glaser W, Balog J, Brandstötter M, Zwerger K, Ammerer G, Hirt H. MP2C, a plant protein phosphatase 2C, functions as a negative regulator of mitogen-activated protein kinase pathways in yeast and plants. Proc Natl Acad Sci U S A 1998; 95:1938-43. [PMID: 9465121 PMCID: PMC19217 DOI: 10.1073/pnas.95.4.1938] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
By interference of the yeast pheromone mitogen-activated protein kinase (MAPK) pathway with an alfalfa cDNA expression library, we have isolated the MP2C gene encoding a functional protein phosphatase type 2C. Epistasis analysis in yeast indicated that the molecular target of the MP2C phosphatase is Ste11, a MAPK kinase kinase that is a central regulator of the pheromone and osmosensing pathways. In plants, MP2C functions as a negative regulator of the stress-activated MAPK (SAMK) pathway that is activated by cold, drought, touch, and wounding. Although activation of the SAMK pathway occurs by a posttranslational mechanism, de novo transcription and translation of protein factor(s) are necessary for its inactivation. MP2C is likely to be this or one of these factors, because wound-induced activation of SAMK is followed by MP2C gene expression and recombinant glutathione S-transferase-MP2C is able to inactivate extracts containing wound-induced SAMK. Wound-induced MP2C expression is a transient event and correlates with the refractory period, i.e., the time when restimulation of the SAMK pathway is not possible by a second stimulation. These data suggest that MP2C is part of a negative feedback mechanism that is responsible for resetting the SAMK cascade in plants.
Collapse
Affiliation(s)
- I Meskiene
- Institute of Microbiology and Genetics, Vienna Biocenter, Dr. Bohrgasse 9, A-1030 Vienna, Austria
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Klumpp S, Selke D, Fischer D, Baumann A, Müller F, Thanos S. Protein phosphatase type-2C isozymes present in vertebrate retinae: purification, characterization, and localization in photoreceptors. J Neurosci Res 1998; 51:328-38. [PMID: 9486768 DOI: 10.1002/(sici)1097-4547(19980201)51:3<328::aid-jnr6>3.0.co;2-i] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Posttranslational modification of proteins by kinases and phosphatases plays an important role in the regulation of cellular signaling in general and neurochemistry in particular. This also applies to vertebrate photoreceptors where phosphorylation of rhodopsin causes uncoupling from the signal transduction cascade. Functional activity of rhodopsin is restored after substitution of the bleached photopigment 11-cisretinal and by dephosphorylation of the opsin moiety. Phosphatases type-1 and type-2A have been identified in vertebrate retinae. Recently, we have shown by molecular cloning that two isozymes of protein phosphatase type-2C (PP2C, PPM) do exist in retinal tissue. In this report, we have purified PP2Calpha and PP2Cbeta from bovine retinae. Thirty to 40% of PP2C was recovered in the cytosolic fraction. Biochemical properties of native and heterologously expressed recombinant enzymes were similar. Enzymatic activity is strictly dependent on the presence of Mg2+. Addition of Ca2+ ions inhibits Mg2+-sustained activity. Antiserum raised against a C-terminal peptide of PP2Cbeta specifically labeled the outer segments of rod photoreceptor cells. PP2C protein levels were significantly reduced in RCS rats, which develop age-dependent photoreceptor degeneration comparable to the hereditary disease retinitis pigmentosa. Although the retinal substrate(s) remain to be identified, the results suggest that PP2C modulates cellular components of the phototransduction machinery.
Collapse
Affiliation(s)
- S Klumpp
- Universität, Pharmazeutische Chemie, Marburg, Germany.
| | | | | | | | | | | |
Collapse
|
34
|
Travis SM, Berger HA, Welsh MJ. Protein phosphatase 2C dephosphorylates and inactivates cystic fibrosis transmembrane conductance regulator. Proc Natl Acad Sci U S A 1997; 94:11055-60. [PMID: 9380758 PMCID: PMC23594 DOI: 10.1073/pnas.94.20.11055] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
cAMP-dependent phosphorylation activates the cystic fibrosis transmembrane conductance regulator (CFTR) in epithelia. However, the protein phosphatase (PP) that dephosphorylates and inactivates CFTR in airway and intestinal epithelia, two major sites of disease, is not certain. We found that in airway and colonic epithelia, neither okadaic acid nor FK506 prevented inactivation of CFTR when cAMP was removed. These results suggested that a phosphatase distinct from PP1, PP2A, and PP2B was responsible. Because PP2C is insensitive to these inhibitors, we tested the hypothesis that it regulates CFTR. We found that PP2Calpha is expressed in airway and T84 intestinal epithelia. To test its activity on CFTR, we generated recombinant human PP2Calpha and found that it dephosphorylated CFTR and an R domain peptide in vitro. Moreover, in cell-free patches of membrane, addition of PP2Calpha inactivated CFTR Cl- channels; reactivation required readdition of kinase. Finally, coexpression of PP2Calpha with CFTR in epithelia reduced the Cl- current and increased the rate of channel inactivation. These results suggest that PP2C may be the okadaic acid-insensitive phosphatase that regulates CFTR in human airway and T84 colonic epithelia. It has been suggested that phosphatase inhibitors could be of therapeutic value in cystic fibrosis; our data suggest that PP2C may be an important phosphatase to target.
Collapse
Affiliation(s)
- S M Travis
- Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, IA 52242, USA
| | | | | |
Collapse
|
35
|
Guthridge MA, Bellosta P, Tavoloni N, Basilico C. FIN13, a novel growth factor-inducible serine-threonine phosphatase which can inhibit cell cycle progression. Mol Cell Biol 1997; 17:5485-98. [PMID: 9271424 PMCID: PMC232397 DOI: 10.1128/mcb.17.9.5485] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We have identified a novel type 2C serine-threonine phosphatase, FIN13, whose expression is induced by fibroblast growth factor 4 and serum in late G1 phase. The protein encoded by FIN13 cDNA includes N- and C-terminal domains with significant homologies to type 2C phosphatases, a domain homologous to collagen, and an acidic domain. FIN13 expression predominates in proliferating tissues. Bacterially expressed FIN13 and FIN13 expressed in mammalian cells exhibit serine-threonine phosphatase activity, which requires Mn2+ and is insensitive to inhibition by okadaic acid. FIN13 is localized in the nuclei of transiently transfected cells. Cotransfection of FIN13-expressing plasmids with a plasmid that expresses the neomycin resistance gene inhibits the growth of drug-resistant colonies in NIH 3T3, HeLa and Rat-1 cells. In transiently transfected cells, FIN13 inhibits DNA synthesis and results in the accumulation of cells in G1 and early S phases. Similarly, the induction of expression of FIN13 under the control of a tetracycline-regulated promoter in NIH 3T3 cells leads to growth inhibition, with accumulation of cells in G1 and early S phases. Thus, overexpression and/or unregulated expression of FIN13 inhibits cell cycle progression, indicating that the physiological role of this phosphatase may be that of regulating the orderly progression of cells through the mitotic cycle by dephosphorylating specific substrates which are important for cell proliferation.
Collapse
Affiliation(s)
- M A Guthridge
- Department of Microbiology and Kaplan Cancer Center, New York University School of Medicine, New York 10016, USA
| | | | | | | |
Collapse
|
36
|
Abstract
We have cloned a novel cDNA from human skeletal muscle which encodes a protein phosphatase with a unique acidic domain. It is 34% identical to mammalian PP2C alpha and PP2C beta and we call it PP2C gamma. It more closely resembles PP2Cs from Paramecium tetraurelia and Schizosaccharomyces pombe than mammalian PP2Cs. Northern blot analysis shows that PP2C gamma is widely expressed, and is most abundant in testis, skeletal muscle, and heart. Like known PP2Cs, recombinant PP2C gamma requires Mg2+ or Mn2+ for activity. Unlike any other known phosphatase, PP2C gamma has a highly acidic domain: 75% of the 54 residues are glutamate or aspartate.
Collapse
Affiliation(s)
- S M Travis
- Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242, USA.
| | | |
Collapse
|
37
|
Ching YP, Kobayashi T, Tamura S, Hardie DG. Specificity of different isoforms of protein phosphatase-2A and protein phosphatase-2C studied using site-directed mutagenesis of HMG-CoA reductase. FEBS Lett 1997; 411:265-8. [PMID: 9271218 DOI: 10.1016/s0014-5793(97)00712-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have expressed the catalytic domain of Chinese hamster HMG-CoA reductase, and 13 point mutations involving the region around the single phosphorylation site for AMP-activated protein kinase. After phosphorylation, these were used to test the specificity of isoforms of protein phosphatase-2A [bovine PP2A(C) (catalytic subunit) and PP2A1 (ABC heterotrimer)] and protein phosphatase-2C (human alpha; mouse alpha, beta1, beta2, beta3, beta4, beta5). PP2A1 had > 50-fold higher activity for HMG-CoA reductase variants than PP2A(C), but their relative selectivity for different variants was similar. Although the specificities of PP2A and PP2C were distinct, no dramatic differences in selectivity were observed between different PP2C isoforms.
Collapse
Affiliation(s)
- Y P Ching
- Biochemistry Department, The University, Dundee, Scotland, UK
| | | | | | | |
Collapse
|
38
|
Marley AE, Sullivan JE, Carling D, Abbott WM, Smith GJ, Taylor IW, Carey F, Beri RK. Biochemical characterization and deletion analysis of recombinant human protein phosphatase 2C alpha. Biochem J 1996; 320 ( Pt 3):801-6. [PMID: 9003365 PMCID: PMC1218000 DOI: 10.1042/bj3200801] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The use of protein phosphatase inhibitors has been instrumental in defining the intracellular roles of protein phosphatase 1 (PP1), PP2A and PP2B. Identification of the role of PP2C in vivo has been hampered, in part, by the unavailability of specific inhibitors. In order to facilitate the identification of novel and specific inhibitors of PP2C by random screening of compounds, and to further characterize this enzyme at the molecular level by site-directed mutagenesis and X-ray crystallography, we have expressed active recombinant human PP2C alpha (rPP2C alpha) in Escherichia coli. Biochemical characterization of rPP2C alpha showed that it could hydrolyse p-nitrophenyl phosphate (pNPP) although, in contrast with native PP2C, this was not stimulated by Mg2+. As with native PP2C, okadaic acid failed to inhibit rPP2C alpha, whereas 50 mM NaF dramatically inhibited its activity. An alignment of the amino acid sequence of AMP-activated protein kinase (AMPK) with those of other serine/threonine protein kinases around the regulatory phosphorylation site (subdomains VII-VIII) revealed a high degree of conservation. Phosphopeptides derived from this region of AMPK and containing the almost invariant threonine (Thr172 in AMPK) were found to be good substrates for rPP2C alpha. We also showed that rPP2C alpha can inactivate AMPK, but only in the presence of Mg2+. To define the regions of PP2C alpha important for catalytic activity, we expressed a number of truncated proteins based on the sequence and proposed domain structure of the PP2C alpha homologue from Paramecium tetraurelia. Deletion of 75 residues (9 kDa) from the C-terminus appeared to have little effect on the catalytic activity using pNPP, phosphopeptides or AMPK as substrates. This suggests that the residues important in catalysis lie elsewhere in the protein. A further deletion of the C-terminus led to a completely inactive and very poorly soluble protein.
Collapse
Affiliation(s)
- A E Marley
- Cardiovascular and Musculoskeletal Research Department, Zeneca Pharmaceuticals, Macclesfield, Cheshire, U.K
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Davies SP, Helps NR, Cohen PT, Hardie DG. 5'-AMP inhibits dephosphorylation, as well as promoting phosphorylation, of the AMP-activated protein kinase. Studies using bacterially expressed human protein phosphatase-2C alpha and native bovine protein phosphatase-2AC. FEBS Lett 1995; 377:421-5. [PMID: 8549768 DOI: 10.1016/0014-5793(95)01368-7] [Citation(s) in RCA: 403] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Human protein phosphatase-2C alpha (PP2C alpha) was purified to homogeneity after expression in Escherichia coli. AMP inhibited the dephosphorylation of AMP-activated protein kinase (AMPK), but not phosphocasein, by PP2C alpha. The concentration dependence and the effects of other nucleotides (ATP and formycin A-5'-monophosphate) suggest that AMP acts by binding to the same site which causes direct allosteric activation of AMPK. A similar, although less pronounced, effect was observed with another protein phosphatase (PP2AC). We have now shown that AMPK activates the AMPK cascade by four mechanisms, which should make the system exquisitely sensitive to changes in AMP concentration.
Collapse
Affiliation(s)
- S P Davies
- Department of Biochemistry, The University, Dundee, Scotland, UK
| | | | | | | |
Collapse
|
40
|
Nishikawa M, Omay SB, Nakai K, Kihira H, Kobayashi T, Tamura S, Shiku H. Up-regulation of protein serine/threonine phosphatase type 2C during 1 alpha,25-dihydroxyvitamin D3-induced monocytic differentiation of leukemic HL-60 cells. FEBS Lett 1995; 375:299-303. [PMID: 7498522 DOI: 10.1016/0014-5793(95)01209-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Treatment with 20 nM 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) caused a progressive increase in the activity of Mg(2+)-dependent protein serine/threonine phosphatase type 2C (PP2C) in subcellular fractions of HL-60 cells, whereas PP2C activity was relatively constant throughout all-trans retinoic acid-induced (1 microM) granulocytic differentiation. The increase in PP2C activity appeared to parallel the 1,25(OH)2D3-induced phenotypic and functional changes in HL-60 cells. Immunoblot and Northern blot analysis indicated that the increase in PP2C activity corresponded to the increased expression of PP2C protein, which was preceded by an increase in the level of mRNA for PP2C beta. No mRNA for PP2C alpha was detected in resting or 1,25(OH)2D3-stimulated HL-60 cells. These results suggest that the increased expression of PP2C is related with the 1,25(OH)2D3-induced monocytic differentiation of HL-60 cells.
Collapse
Affiliation(s)
- M Nishikawa
- 2nd Department of Internal Medicine, Mie University School of Medicine, Japan
| | | | | | | | | | | | | |
Collapse
|
41
|
Wang Y, Santini F, Qin K, Huang CY. A Mg(2+)-dependent, Ca(2+)-inhibitable serine/threonine protein phosphatase from bovine brain. J Biol Chem 1995; 270:25607-12. [PMID: 7592734 DOI: 10.1074/jbc.270.43.25607] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The Mg(2+)-dependent serine/threonine protein phosphatases, also known as type 2C phosphatases (PP2C), belong to a gene family distinct from the other serine/threonine phosphatases and tyrosine phosphatases. Here we report the purification to apparent homogeneity of a novel Mg(2+)-dependent, Ca(2+)-inhibitable serine/threonine protein phosphatase from bovine brain. It is a type 2C enzyme in view of its Mg2+ requirement, resistance to okadaic acid and calyculin A, inability to use phosphorylase alpha as substrate, and a segment of amino acid sequence typical of all PP2C type phosphatases known to date. However, it differs from the other PP2C enzymes, particularly the mammalian PP2C alpha and -beta isoforms, in that its molecular weight, 76,000, is considerably larger and that it is inhibited by Ca2+, NaF, and polycations, but not by orthovanadate. The Ca2+ inhibition may not be related to its cellular regulation because of Ki values in the 20-90 microM range, but this property permits distinction of this enzyme from the other phosphatases. Although the precise physiological role of this phosphatase is not yet known, its ability to dephosphorylate a wide variety of phosphoproteins and its broad distribution, as shown by a survey of mouse tissues for its activity, suggest that it may serve an important cellular function.
Collapse
Affiliation(s)
- Y Wang
- Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | |
Collapse
|
42
|
Klumpp S, Hanke C, Donella-Deana A, Beyer A, Kellner R, Pinna LA, Schultz JE. A membrane-bound protein phosphatase type 2C from Paramecium tetraurelia. Purification, characterization, and cloning. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(20)30058-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
43
|
Stone JM, Collinge MA, Smith RD, Horn MA, Walker JC. Interaction of a protein phosphatase with an Arabidopsis serine-threonine receptor kinase. Science 1994; 266:793-5. [PMID: 7973632 DOI: 10.1126/science.7973632] [Citation(s) in RCA: 170] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A protein phosphatase was cloned that interacts with a serine-threonine receptor-like kinase, RLK5, from Arabidopsis thaliana. The phosphatase, designated KAPP (kinase-associated protein phosphatase), is composed of three domains: an amino-terminal signal anchor, a kinase interaction (KI) domain, and a type 2C protein phosphatase catalytic region. Association of RLK5 with the KI domain is dependent on phosphorylation of RLK5 and can be abolished by dephosphorylation. KAPP may function as a signaling component in a pathway involving RLK5.
Collapse
Affiliation(s)
- J M Stone
- Department of Biochemistry, University of Missouri-Columbia 65211
| | | | | | | | | |
Collapse
|
44
|
Mannhaupt G, Stucka R, Ehnle S, Vetter I, Feldmann H. Analysis of a 70 kb region on the right arm of yeast chromosome II. Yeast 1994; 10:1363-81. [PMID: 7900426 DOI: 10.1002/yea.320101014] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
In the framework of the EC programme for sequencing yeast chromosome II, we have determined the nucleotide sequence of a 70 kb region. Subsequent analysis revealed 35 open reading frames, 14 of which correspond to known yeast genes. From structural parameters and/or similarity searches with entries in the current data libraries, a preliminary functional assessment of several of the putative novel gene products can be made. The gene density in this region amounts to one gene in 1.98 kb. Coding regions occupy 75% of the total DNA sequence. Within the intergenic regions, potential regulatory elements can be predicted. The data obtained here may serve as a basis for a more detailed biochemical analysis of the novel genes.
Collapse
Affiliation(s)
- G Mannhaupt
- Institut für Physiologische Chemie, Universität München, Germany
| | | | | | | | | |
Collapse
|
45
|
Kato S, Kobayashi T, Terasawa T, Ohnishi M, Sasahara Y, Kanamaru R, Tamura S. The cDNA sequence encoding mouse Mg2+ -dependent protein phosphatase alpha. Gene 1994; 145:311-2. [PMID: 8056349 DOI: 10.1016/0378-1119(94)90026-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The complete cDNA sequence encoding Mg2+ -dependent protein phosphatase (MPP) alpha from mouse brain was cloned. It encodes a protein of 382 amino acids with a calculated M(r) of 42,432. The putative sites of phosphorylation by casein kinase II, found originally in rat MPP alpha, are conserved in the mouse ortholog.
Collapse
Affiliation(s)
- S Kato
- Department of Biochemistry, Tohoku University, Sendai, Japan
| | | | | | | | | | | | | |
Collapse
|
46
|
TPD1 of Saccharomyces cerevisiae encodes a protein phosphatase 2C-like activity implicated in tRNA splicing and cell separation. Mol Cell Biol 1994. [PMID: 8196609 DOI: 10.1128/mcb.14.6.3634] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Saccharomyces cerevisiae TPD1 gene has been implicated in tRNA splicing because a tpd1-1 mutant strain accumulates unspliced precursor tRNAs at high temperatures (W. H. van Zyl, N. Wills, and J. R. Broach, Genetics 123:55-68, 1989). The wild-type TPD1 gene was cloned by complementation of the tpd1-1 mutation and shown to encode a protein with substantial homology to protein phosphatase 2C (PP2C) of higher eukaryotes. Expression of Tpd1p in Escherichia coli results in PP2C-like activity. Strains deleted for the TPD1 gene exhibit multiple phenotypes: temperature-sensitive growth, accumulation of unspliced precursor tRNAs, sporulation defects, and failure of cell separation during mitotic growth. On the basis of the presence of these observable phenotypes and the fact that Tpd1p accounts for a small percentage of the observed PP2C activity, we argue that Tpd1p is a unique member of the PP2C family.
Collapse
|
47
|
Protein phosphatase 2C, encoded by ptc1+, is important in the heat shock response of Schizosaccharomyces pombe. Mol Cell Biol 1994. [PMID: 8196617 DOI: 10.1128/mcb.14.6.3742] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein phosphatase 2C (PP2C), an Mg(2+)-dependent enzyme that dephosphorylates serine and threonine residues, defines one of the three major families of structurally unrelated eukaryotic protein phosphatases. Members of the two other families of protein phosphatases are known to have important cellular roles, but very little is known about the biological functions of PP2C. In this report we describe a genetic investigation of a PP2C enzyme in the fission yeast Schizosaccharomyces pombe. We discovered ptc1+ (phosphatase two C) as a multicopy suppressor gene of swo1-26, a temperature-sensitive mutation of a gene encoding the heat shock protein hsp90. The ptc1+ gene product is a 40-kDa protein with approximately 24% identity to a rat PP2C protein. Purified Ptc1 has Mg(2+)-dependent casein phosphatase activity, confirming that it is a PP2C enzyme. A ptc1 deletion mutant is viable and has approximately normal levels of PP2C activity, observations consistent with the fact that ptc1+ is a member of a multigene family. Although a ptc1 deletion mutant is viable, it has a greatly reduced ability to survive brief exposure to elevated temperature. Moreover, ptc1+ mRNA levels increase 5- to 10-fold during heat shock. These data, demonstrating that Ptc1 activity is important for survival of heat shock, provide one of the first genetic clues as to the biological functions of PP2C.
Collapse
|
48
|
Shiozaki K, Akhavan-Niaki H, McGowan CH, Russell P. Protein phosphatase 2C, encoded by ptc1+, is important in the heat shock response of Schizosaccharomyces pombe. Mol Cell Biol 1994; 14:3742-51. [PMID: 8196617 PMCID: PMC358741 DOI: 10.1128/mcb.14.6.3742-3751.1994] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Protein phosphatase 2C (PP2C), an Mg(2+)-dependent enzyme that dephosphorylates serine and threonine residues, defines one of the three major families of structurally unrelated eukaryotic protein phosphatases. Members of the two other families of protein phosphatases are known to have important cellular roles, but very little is known about the biological functions of PP2C. In this report we describe a genetic investigation of a PP2C enzyme in the fission yeast Schizosaccharomyces pombe. We discovered ptc1+ (phosphatase two C) as a multicopy suppressor gene of swo1-26, a temperature-sensitive mutation of a gene encoding the heat shock protein hsp90. The ptc1+ gene product is a 40-kDa protein with approximately 24% identity to a rat PP2C protein. Purified Ptc1 has Mg(2+)-dependent casein phosphatase activity, confirming that it is a PP2C enzyme. A ptc1 deletion mutant is viable and has approximately normal levels of PP2C activity, observations consistent with the fact that ptc1+ is a member of a multigene family. Although a ptc1 deletion mutant is viable, it has a greatly reduced ability to survive brief exposure to elevated temperature. Moreover, ptc1+ mRNA levels increase 5- to 10-fold during heat shock. These data, demonstrating that Ptc1 activity is important for survival of heat shock, provide one of the first genetic clues as to the biological functions of PP2C.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Cloning, Molecular
- DNA, Complementary/chemistry
- DNA, Fungal/chemistry
- DNA, Fungal/metabolism
- Gene Expression Regulation, Enzymologic
- Gene Expression Regulation, Fungal
- Genes, Fungal
- Hot Temperature
- Molecular Sequence Data
- Mutagenesis, Insertional
- Open Reading Frames
- Phosphoprotein Phosphatases/biosynthesis
- Phosphoprotein Phosphatases/genetics
- Phosphoprotein Phosphatases/metabolism
- Protein Phosphatase 2
- Protein Phosphatase 2C
- RNA, Messenger/biosynthesis
- Rats
- Recombinant Fusion Proteins/metabolism
- Restriction Mapping
- Saccharomyces cerevisiae Proteins
- Schizosaccharomyces/enzymology
- Schizosaccharomyces/genetics
- Schizosaccharomyces/physiology
- Sequence Deletion
- Sequence Homology, Amino Acid
Collapse
Affiliation(s)
- K Shiozaki
- Department of Molecular Biology, Scripps Research Institute, La Jolla, California 92037
| | | | | | | |
Collapse
|
49
|
Robinson MK, van Zyl WH, Phizicky EM, Broach JR. TPD1 of Saccharomyces cerevisiae encodes a protein phosphatase 2C-like activity implicated in tRNA splicing and cell separation. Mol Cell Biol 1994; 14:3634-45. [PMID: 8196609 PMCID: PMC358731 DOI: 10.1128/mcb.14.6.3634-3645.1994] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The Saccharomyces cerevisiae TPD1 gene has been implicated in tRNA splicing because a tpd1-1 mutant strain accumulates unspliced precursor tRNAs at high temperatures (W. H. van Zyl, N. Wills, and J. R. Broach, Genetics 123:55-68, 1989). The wild-type TPD1 gene was cloned by complementation of the tpd1-1 mutation and shown to encode a protein with substantial homology to protein phosphatase 2C (PP2C) of higher eukaryotes. Expression of Tpd1p in Escherichia coli results in PP2C-like activity. Strains deleted for the TPD1 gene exhibit multiple phenotypes: temperature-sensitive growth, accumulation of unspliced precursor tRNAs, sporulation defects, and failure of cell separation during mitotic growth. On the basis of the presence of these observable phenotypes and the fact that Tpd1p accounts for a small percentage of the observed PP2C activity, we argue that Tpd1p is a unique member of the PP2C family.
Collapse
Affiliation(s)
- M K Robinson
- Department of Biochemistry, University of Rochester Medical School, New York 14642
| | | | | | | |
Collapse
|
50
|
Mutations in a protein tyrosine phosphatase gene (PTP2) and a protein serine/threonine phosphatase gene (PTC1) cause a synthetic growth defect in Saccharomyces cerevisiae. Mol Cell Biol 1993. [PMID: 8395005 DOI: 10.1128/mcb.13.9.5408] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two protein tyrosine phosphatase genes, PTP1 and PTP2, are known in Saccharomyces cerevisiae. However, the functions of these tyrosine phosphatases are unknown, because mutations in either or both phosphatase genes have no clear phenotypic effects. In this report, we demonstrate that although ptp2 has no obvious phenotype by itself, it has a profound effect on cell growth when combined with mutations in a novel protein phosphatase gene. Using a colony color sectoring assay, we isolated 25 mutants in which the expression of PTP1 or PTP2 is required for growth. Complementation tests of the mutants showed that they have a mutation in one of three genes. Cloning and sequence determination of one of these gene, PTC1, indicated that it encodes a homolog of the mammalian protein serine/threonine phosphatase 2C (PP2C). The amino acid sequence of the PTC1 product is approximately 35% identical to PP2C. Disruption of PTC1 indicated that the PTC1 function is nonessential. In contrast, ptc1 ptp2 double mutants showed a marked growth defect. To examine whether PTC1 encodes an active protein phosphatase, a glutathione S-transferase (GST)-PTC1 fusion gene was constructed and expressed in Escherichia coli. Purified GST-PTC1 fusion protein hydrolyzed a serine phosphorylated substrate in the presence of the divalent cation Mg2+ or Mn2+. GST-PTC1 also had weak (approximately 0.5% of its serine phosphatase activity) protein tyrosine phosphatase activity.
Collapse
|